Microbial population dynamics under microdoses of the essential oil arborvitae.

Background: With the current concern caused by drug resistant microorganisms, alternatives to traditional antimicrobials are increasingly necessary. Historical holistic treatments involving natural approaches are now of interest as a potential alternative. Many essential oils have antimicrobial properties with the ability to modify bacterial and fungal population dynamics in low concentrations.

Effect of farnesol on a mouse model of systemic candidiasis, determined by use of a DPP3 knockout mutant of Candida albicans.

This work extends our previous observation that the fungus Candida albicans secretes micromolar levels of farnesol and that accumulation of farnesol in vitro prevents the yeast-to-mycelium conversion in a quorum-sensing manner. What does farnesol do in vivo? The purpose of this study was to determine the role of farnesol during infection with a well-established mouse model of systemic candidiasis with C. albicans A72 administered by tail vein injection.

Farnesol restores wild-type colony morphology to 96% of Candida albicans colony morphology variants recovered following treatment with mutagens.

Candida albicans is a diploid fungus that undergoes a morphological transition between budding yeast, hyphal, and pseudohyphal forms. The morphological transition is strongly correlated with virulence and is regulated in part by quorum sensing. Candida albicans produces and secretes farnesol that regulates the yeast to mycelia morphological transition.

Farnesol-induced apoptosis in Aspergillus nidulans reveals a possible mechanism for antagonistic interactions between fungi.

The dimorphic fungus Candida albicans secretes farnesol, which acts as a quorum-sensing molecule and prevents the yeast to mycelium conversion. In this study we examined the effect of farnesol in the filamentous fungus Aspergillus nidulans. We show that externally added farnesol has no effect on hyphal morphogenesis; instead, it triggers morphological features characteristic of apoptosis.

Enhanced pathogenicity of Candida albicans pre-treated with subinhibitory concentrations of fluconazole in a mouse model of disseminated candidiasis.

Objectives: To investigate the relative pathogenicity of Candida albicans treated with subinhibitory concentrations of fluconazole in a mouse model of disseminated candidiasis. Previous studies indicate that these cells secrete 10 times more farnesol than do untreated cells. In our usage, subinhibitory means a concentration which causes a prominent decrease in turbidity but still allows some cell growth.

Farnesol concentrations required to block germ tube formation in Candida albicans in the presence and absence of serum.

Concentrations of (E,E)-farnesol needed to inhibit germ tube formation were determined for Candida albicans strains A72 and SC5314 by using six different conditions known to trigger germination. For defined media, 1 to 2 microM farnesol was sufficient. However, with serum at 2 to 20%, up to 250 microM farnesol was required.

Defined anaerobic growth medium for studying Candida albicans basic biology and resistance to eight antifungal drugs.

The polymorphic fungus Candida albicans is one of the most versatile opportunistic pathogens in humans. Many organs of the human body are potential targets for infection by this pathogen, but infection is commonly localized in the gastrointestinal tract, an environment providing anaerobic growth conditions. We describe a chemically defined anaerobic growth medium for four strains of Candida albicans (A72, SC5314, MEN, and 10261).

Enhanced production of farnesol by Candida albicans treated with four azoles.

The dimorphic fungus Candida albicans excretes farnesol, which is produced enzymatically from the sterol biosynthetic intermediate farnesyl pyrophosphate. Inhibition of C. albicans by four azole antifungals, fluconazole, ketoconazole, miconazole, and clotrimazole, caused elevated farnesol production (10- to 45-fold).

Inoculum size effect in dimorphic fungi: extracellular control of yeast-mycelium dimorphism in Ceratocystis ulmi.

We studied the inoculum size effect in Ceratocystis ulmi, the dimorphic fungus that causes Dutch elm disease. In a defined glucose-proline-salts medium, cells develop as budding yeasts when inoculated at > or = 10(6) spores per ml and as mycelia when inoculated at <10(6) spores per ml. The inoculum size effect was not influenced by inoculum spore type, age of the spores, temperature, pH, oxygen availability, trace metals, sulfur source, phosphorous source, or the concentration of glucose or proline.

High phosphate (up to 600 mM) induces pseudohyphal development in five wild type Candida albicans.

A method is described for the formation of nearly 100% pseudohyphae populations of wild-type Candida albicans A72. The method employs fungal growth at 37 degrees C (ca. 5x10(6) cells/ml) in a glucose-proline-N-acetyl-glucosamine medium supplemented with up to 600 mM phosphate (KH(2)PO(4)/K(2)HPO(4) 1:1) at pH 6.

Quorum sensing in Candida albicans: probing farnesol's mode of action with 40 natural and synthetic farnesol analogs.

The dimorphic fungus Candida albicans produces extracellular farnesol (3,7,11-trimethyl-2,6,10-dodecatriene-1-ol) which acts as a quorum-sensing molecule (QSM) to suppress filamentation. Of four possible geometric isomers of farnesol, only the E,E isomer possesses QSM activity. We tested 40 natural and synthetic analogs of farnesol for their activity in an N-acetylglucosamine-induced differentiation assay for germ tube formation (GTF).

Farnesol biosynthesis in Candida albicans: cellular response to sterol inhibition by zaragozic acid B.

The dimorphic fungus Candida albicans produces farnesol as a quorum-sensing molecule that regulates cellular morphology. The biosynthetic origin of farnesol has been resolved by treating these cells with zaragozic acid B, a potent inhibitor of squalene synthase in the sterol biosynthetic pathway. Treatment with zaragozic acid B leads to an eightfold increase in the amount of farnesol produced by C.